The performance of many devices that are fabricated using semiconductor methods is critically dependent upon the three-dimensional (3D) structure thereof. For example, the performance of a perpendicular magnetic recording (PMR) write pole is highly dependent upon the 3D shape of the write pole near the air bearing surface (ABS), the nose length, and pole flare and/or pinching. To obtain information about the efficacy of manufacturing methods of these and other devices, it is desirable to measure the 3D structure of these devices when comparing the performance of different designs.
One approach to measuring the 3D structure of a device in a wafer involves a “slice and view” (SnV) method employing a dual beam Focused-Ion-Beam Scanning Electron Microscope (FIB/SEM). In this method, the FIB is employed to make a cut or trench in the 3D structure, a facet of which is then imaged with the SEM. Unfortunately, the accuracy with which the initial cut or trench can be placed is limited by the hardware, and may be sufficiently large to preclude precisely imaging a desired plane. For example, if the initial placement has an uncertainty of 25 nm, the precise imaging of an ABS of a PMR write pole may be rendered difficult, as many different poles may have to be cut before a facet is formed through one acceptably close (e.g., within 5 nm) to the ABS thereof.